Significant progress has been made in Vitro Fertilization (IVF) since the fist test tube baby was born in 1978. IVF pregnancy success rates in the U.S. have reached an average of 35% for all patient sub- populations (National Summary and Fertility Clinic Report, 2005), with some clinics reporting success rates as high as 60%. To improve the percentage of cycles resulting in live births, the industry relies on transferring an average of 3 embryos per cycle, leading to multiple births in more than one-third of all cases, which in turn, increases risks to both the fetus and the mother. Maintaining pregnancy rates while limiting the number of embryos transferred would require obtaining sufficient quantities of high quality, advanced-stage embryos of high implantation and pregnancy potential. For many clinics, extended culture beyond the 8-cell stage, which is the only available method to obtain and select advanced-stage preimplantation embryos, involves significant risk of embryo loss due to suboptimal culture conditions. New technologies are needed to maximize the development potential of genetically healthy embryos in culture. The long term goal for this proposal is to develop an automated microfluidic embryo culture system to improve preimplantation human embryo development rate and quality for IVF treatment. Early prototypes of this system have been developed and have shown accelerated mouse embryo developmental rate and improved quality as assessed by higher percentages of advanced-stage blastocysts and increased cell formation at 96 hours. Yet, additional technology innovations and testing are needed to demonstrate that the system is capable of enhancing implantation and pregnancy rates in mice as well as to develop devices compatible for use with human embryos. The specific aims in this Phase I project are: 1) Optimize current microfluidic chip prototypes for end user- friendly manipulation to support future human clinical trials. 2) Validate that the effects of microfluidic partial media refreshment on embryos will enhance implantation and pregnancy rates in mice when compared to conventional microdrop or dish-cultured embryos. The development of a computerized microfluidic embryo culture system would be a highly innovative and important advancement for producing high quality embryos for fertility therapy, which will lead to fewer embryos needed for transfer to establish a pregnancy, and more embryos for freezing and overall greater live- birth rate per stimulation cycle. The potential long-term benefit is that by removing inefficiencies in current embryo culture, one can envision future success with natural cycle IVF (no hormones). In this regard, the development of new computer controlled microfluidic chip technology for IVF has promising commercial potential and could provide significant health benefits to the 7 million people facing infertility in the U.S. The development of microfluidic embryo culture technologies directly addresses the reduction of high incidences of multiple births resulting from In Vitro Fertilization, a growing societal concern for treating infertility. The technology also provides an outstanding research platform to assess the physiologic factors affecting early preimplantation embryo and blastocyst development. This project will advance current technologies that provide near physiologic conditions to improve the developmental rate and cell formation for early stage embryos. [unreadable] [unreadable] [unreadable]